Massachusetts Rep. Niki Tsongas announced Wednesday she won’t be seeking a sixth full term in 2018.

“I have learned in life that there is a time for endings and for beginnings. After much thought, I have decided that this is one of those times,” Tsongas said in a statement.

The Lowell Democrat will serve out the rest of her term, leaving behind a safely Democratic 3rd District seat that Hillary Clinton carried by more than 20 points last fall.

In announcing her retirement, Tsongas drew attention to her initial desire for running: to get more women elected.

“I’m proud that my election marked the first time in a quarter century that Massachusetts sent a woman to Congress,” Tsongas said. She was first elected in a 2007 special election in what was then the 5th District.

“Since that door cracked open, the Commonwealth has elected another female member of Congress, our first female US Senator, and in my district, 50% of our state legislators are now women, paving the way for even more women from our state to serve in political office bringing their voices to all we value as a country,” she said in her statement.

Since her election, Tsongas has been joined by Sen. Elizabeth Warren and 5th District Rep. Katherine M. Clark to make three women in the 11-member Massachusetts delegation.

Tsongas, a member of the Armed Services Committee, also called attention Wednesday to her work against sexual assault in the military.

“I’m especially proud of the role I have been able to play in challenging the ways in which women are treated in the military, understanding that if you change the culture of one of our country’s rightly honored bedrock institutions, you can change a country,” Tsongas said.

Her late husband, Paul Tsongas, was a two-term House member and served a term in the Senate. He ran for president in 1992 before dying of cancer in 1997.

Inside Elections with Nathan L. Gonzales rates the 3rd District contest Solid Democratic. Tsongas won re-election by 38 points last fall and with her out of the race, a crowded Democratic primary appears likely. Democrats mentioned Lawrence Mayor Daniel Rivera and former state Sen. Barry Finegold as potential candidates. Finegold lost the 2007 primary for the 3rd District to Tsongas. He also ran unsuccessfully for the Democratic nod for state treasurer in 2014.

State Sen. Barbara L’Italien released a statement Wednesday afternoon praising Tsongas and saying she’s looking at the race herself.

“I am eagerly exploring the opportunity of running for this Congressional seat and how to best continue in Niki’s footsteps as an indefatigable advocate for the priorities of the women, men, and children of the 3rd District,” L’Italien said.

Correction 1:21 p.m. | An earlier version of the story misidentified the year Tsongas was first elected to Congress and the original congressional district from which she was elected.